Tighten up CSS

- Remove extra padding at top of Android bubbles, via sibling selector
- Don't include .attachments, .quote-wrapper, .content in bubble unless
  we actually need them. This allows for sibling selectors.
- This is a different technique for adding the ReactWrapperView for
  quotes - it is now appended to the DOM instead of attaching to
  something already in the DOM. This allows us to use .remove(), so it's
  a bit cleaner.
- Users of ReactWrapperView can now specify tagName and className

ts/components/conversation/Message.tsx

@@ -15,7 +15,6 @@ export class Message extends React.Component<{}, {}> {
           <div className="sender" dir="auto" />
           <div className="tail-wrapper with-tail">
             <div className="inner-bubble">
-              <div className="attachments" />
               <p className="content" dir="auto">
                 <span className="body">
                   Hi there. How are you doing? Feeling pretty good? Awesome.